Re: [PATCH v2 00/16] perf arm64: Support data type profiling

[James Clark <james.clark@linaro.org>]

On 17/04/2026 02:53, Tengda Wu wrote:
> 
> 
> On 2026/4/16 23:31, James Clark wrote:
>>
>>
>> On 03/04/2026 10:47, Tengda Wu wrote:
>>> This patch series implements data type profiling support for arm64,
>>> building upon the foundational work previously contributed by Huafei [1].
>>> While the initial version laid the groundwork for arm64 data type analysis,
>>> this series iterates on that work by refining instruction parsing and
>>> extending support for core architectural features.
>>>
>>> The series is organized as follows:
>>>
>>> 1. Fix disassembly mismatches (Patches 01-02)
>>>      Current perf annotate supports three disassembly backends: llvm,
>>>      capstone, and objdump. On arm64, inconsistencies between the output
>>>      of these backends (specifically llvm/capstone vs. objdump) often
>>>      prevent the tracker from correctly identifying registers and offsets.
>>>      These patches resolve these mismatches, ensuring consistent instruction
>>>      parsing across all supported backends.
>>>
>>> 2. Infrastructure for arm64 operand parsing (Patches 03-07)
>>>      These patches establish the necessary infrastructure for arm64-specific
>>>      operand handling. This includes implementing new callbacks and data
>>>      structures to manage arm64's unique addressing modes and register sets.
>>>      This foundation is essential for the subsequent type-tracking logic.
>>>
>>> 3. Core instruction tracking (Patches 08-16)
>>>      These patches implement the core logic for type tracking on arm64,
>>>      covering a wide range of instructions including:
>>>
>>>      * Memory Access: ldr/str variants (including stack-based access).
>>>      * Arithmetic & Data Processing: mov, add, and adrp.
>>>      * Special Access: System register access (mrs) and per-cpu variable
>>>        tracking.
>>>
>>> The implementation draws inspiration from the existing x86 logic while
>>> adapting it to the nuances of the AArch64 ISA [2][3]. With these changes,
>>> perf annotate can successfully resolve memory locations and register
>>> types, enabling comprehensive data type profiling on arm64 platforms.
>>>
>>> Example Result
>>> ==============
>>>
>>> # perf mem record -a -K -- sleep 1
>>> # perf annotate --data-type --type-stat --stdio
>>
>> Hi Tengda,
>>
>> Did you run this with any itrace options? If I run your command I get repeated blocks of duplicate stats and types, which is very confusing. One for each sample type that we generate decoding SPE.
>>
>> For example the default perf report output has all these groups:
>>
>>    Available samples
>>    0 arm_spe_0/
>>      ts_enable=1,pa_enable=1,load_filter=1,store_filter=1,min_latency=30/
>>    0 dummy:u
>>    3 l1d-miss
>>    18 l1d-access
>>    0 llc-miss
>>    0 llc-access
>>    0 tlb-miss
>>    22 tlb-access
>>    0 branch
>>    0 remote-access
>>    22 memory
>>    22 instructions
>>
>> Obviously there are 22 samples total (instructions) and they get duplicated into whatever other categories they happen to have flags for.
>>
> 
> Yes, I agree. The duplication makes the type stats misleading.
> De-duplication is definitely necessary here.
> 
>> To remove the duplicates you have to do --itrace=i1i. Could that need to be default for perf annotate with SPE?
>>
> I'll look into making this the default behavior for SPE data-type
> annotation.
> 
>>> Annotate data type stats:
>>> total 6204, ok 5091 (82.1%), bad 1113 (17.9%)
>>> -----------------------------------------------------------
>>>           29 : no_sym
>>>          196 : no_var
>>>          806 : no_typeinfo
>>>           82 : bad_offset
>>>         1370 : insn_track
>>>
> 
> Here are the results with --itrace=i1i (a slight decrease in accuracy):
> 
> Annotate data type stats:
> total 1138, ok 877 (77.1%), bad 261 (22.9%)

I'm still it a bit confused why you seem to get a 'total' count that is 
a sum of all the sample groups, if it went from 6204 to 1138 when you 
only asked for the instructions samples. Whereas I get separate groups, 
and asking for only instructions samples doesn't change the value for 
the last 'total', it just removes the other outputs.

It shouldn't change the accuracy either because the instruction group is 
the top level one which contains all of the samples.

> -----------------------------------------------------------
>           6 : no_sym
>          44 : no_var
>         197 : no_typeinfo
>          14 : bad_offset
>         238 : insn_track
> 
> This will be the new baseline, and I will work on further optimizations
> from here.
> 
> Best regards,
> Tengda
> 
>>> Annotate type: 'struct page' in [kernel.kallsyms] (59208 samples):
>>> ============================================================================
>>>    Percent     offset       size  field
>>>     100.00          0       0x40  struct page      {
>>>       9.95          0        0x8      long unsigned int   flags;
>>>      52.83        0x8       0x28      union        {
>>>      52.83        0x8       0x28          struct   {
>>>      37.21        0x8       0x10              union        {
>>>      37.21        0x8       0x10                  struct list_head        lru {
>>>      37.21        0x8        0x8                      struct list_head*   next;
>>>       0.00       0x10        0x8                      struct list_head*   prev;
>>>                                                   };
>>>      37.21        0x8       0x10                  struct   {
>>>      37.21        0x8        0x8                      void*       __filler;
>>>       0.00       0x10        0x4                      unsigned int        mlock_count;
>>>      ...
>>>
>>> Changes since v1: (reworked from Huafei's series):
>>>
>>>    - Fix inconsistencies in arm64 instruction output across llvm, capstone,
>>>      and objdump disassembly backends.
>>>    - Support arm64-specific addressing modes and operand formats. (Leo Yan)
>>>    - Extend instruction tracking to support mov and add instructions,
>>>      along with per-cpu and stack variables.
>>>    - Include real-world examples in commit messages to demonstrate
>>>      practical effects. (Namhyung Kim)
>>>    - Improve type-tracking success rate (type stat) from 64.2% to 82.1%.
>>>      https://lore.kernel.org/all/20250314162137.528204-1-lihuafei1@huawei.com/
>>>
>>> Please let me know if you have any feedback.
>>>
>>> Thanks,
>>> Tengda
>>>
>>> [1] https://lore.kernel.org/all/20250314162137.528204-1-lihuafei1@huawei.com/
>>> [2] https://developer.arm.com/documentation/102374/0103
>>> [3] https://github.com/flynd/asmsheets/releases/tag/v8
>>>
>>> ---
>>>
>>> Tengda Wu (16):
>>>     perf llvm: Fix arm64 adrp instruction disassembly mismatch with
>>>       objdump
>>>     perf capstone: Fix arm64 jump/adrp disassembly mismatch with objdump
>>>     perf annotate-arm64: Generalize arm64_mov__parse to support standard
>>>       operands
>>>     perf annotate-arm64: Handle load and store instructions
>>>     perf annotate: Introduce extract_op_location callback for
>>>       arch-specific parsing
>>>     perf dwarf-regs: Adapt get_dwarf_regnum() for arm64
>>>     perf annotate-arm64: Implement extract_op_location() callback
>>>     perf annotate-arm64: Enable instruction tracking support
>>>     perf annotate-arm64: Support load instruction tracking
>>>     perf annotate-arm64: Support store instruction tracking
>>>     perf annotate-arm64: Support stack variable tracking
>>>     perf annotate-arm64: Support 'mov' instruction tracking
>>>     perf annotate-arm64: Support 'add' instruction tracking
>>>     perf annotate-arm64: Support 'adrp' instruction to track global
>>>       variables
>>>     perf annotate-arm64: Support per-cpu variable access tracking
>>>     perf annotate-arm64: Support 'mrs' instruction to track 'current'
>>>       pointer
>>>
>>>    .../perf/util/annotate-arch/annotate-arm64.c  | 642 +++++++++++++++++-
>>>    .../util/annotate-arch/annotate-powerpc.c     |  10 +
>>>    tools/perf/util/annotate-arch/annotate-x86.c  |  88 ++-
>>>    tools/perf/util/annotate-data.c               |  72 +-
>>>    tools/perf/util/annotate-data.h               |   7 +-
>>>    tools/perf/util/annotate.c                    | 108 +--
>>>    tools/perf/util/annotate.h                    |  12 +
>>>    tools/perf/util/capstone.c                    | 107 ++-
>>>    tools/perf/util/disasm.c                      |   5 +
>>>    tools/perf/util/disasm.h                      |   5 +
>>>    .../util/dwarf-regs-arch/dwarf-regs-arm64.c   |  20 +
>>>    tools/perf/util/dwarf-regs.c                  |   2 +-
>>>    tools/perf/util/include/dwarf-regs.h          |   1 +
>>>    tools/perf/util/llvm.c                        |  50 ++
>>>    14 files changed, 984 insertions(+), 145 deletions(-)
>>>
>>>
>>> base-commit: cf7c3c02fdd0dfccf4d6611714273dcb538af2cb
>